New Hampshire wetlands and waters: Results of the National Wetlands Inventory

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Cover Photo: Audubon Society of New Hampshire’s Thompson Sanctuary wetlands by
Eric Derleth, U.S. Fish & Wildlife Service.
New Hampshire Wetlands and Waters:
Results of the National Wetlands Inventory
Ralph W. Tiner
U.S. Fish & Wildlife Service
National Wetlands Inventory Program
Northeast Region
300 Westgate Center Drive
Hadley, MA 01035
August 2007
This report should be cited as:
Tiner, R.W. 2007. New Hampshire Wetlands and Waters: Results of the National
Wetlands Inventory. U.S. Fish and Wildlife Service, Northeast Region, Hadley, MA.
NWI Technical Report. 21 pp.
Note: The findings and conclusions in the report are those of the author and do not
necessarily represent the views of the U.S. Fish and Wildlife Service.
TABLE OF CONTENTS
Page
Introduction 1
Study Area 1
Methods 4
Results 8
Wetland Maps 8
State Totals 9
County Totals 9
Discussion 17
Comparison with Hydric Soils Acreage 17
Conclusion 19
Acknowledgments 20
References 21
This page is intentionally blank.
1
INTRODUCTION
The U.S. Fish and Wildlife Service (FWS) has been conducting a nationwide survey of
wetlands and deepwater habitats since the mid-1970s through its National Wetlands
Inventory Program (NWI). This survey is accomplished using traditional
photointerpretation techniques to produces map and digital geospatial data on the status
of wetlands. The U.S. Geological Survey topographic maps serve as the base data upon
which boundaries of wetlands and deepwater habitats are delineated. Wetlands are
classified according to the FWS’s official wetland classification system (Cowardin et al.
1979) which has been adopted as the national standard for reporting on the status and
trends of U.S. wetlands by the Federal Geographic Data Committee
(http://www.fws.gov/stand/standards/wetlands.txt).
Wetland mapping has been completed for over 90% of the coterminous U.S., all of
Hawaii, and 35% of Alaska. For the Northeast, wetland mapping has been completed for
12 of the 13 states in the region; all but New York have been completely mapped. As
time permits, the FWS summarizes the results of its NWI for geographic areas. Detailed
state reports have been prepared for several states (Connecticut, Delaware, Maryland, and
New Jersey), while data summary reports have been prepared for several other states in
the northeastern United States: Massachusetts, Vermont, Pennsylvania, and West
Virginia.
Wetland mapping for New Hampshire was completed in the 1990s and the data have
been available online for several years. The data have not been summarized; this report
provides a summary of the findings of the inventory.
Study Area
The state of New Hampshire encompasses 9,350 square miles in the northeastern United
States. It ranks 46th among states in size and 41th in population as of 2005. The state
contains 8,969 square miles of land and 382 square miles of water
(http://infoplease.com).
From a natural landscape standpoint, the state falls within two of Bailey’s ecoregions:
Adirondack-New England Mixed Forest-Coniferous Forest-Alpine Meadow Province and
Eastern Broadleaf Forest (Oceanic) Province (Bailey 1995). Due to its glacial history,
the state contains numerous lakes and ponds with Lake Winnipesaukee being the largest
(44,586 acres) and the most well-known. It is nearly seven times bigger than New
Hampshire’s next largest lake – Umbagog Lake (7,539 acres). Among the more
prominent rivers are the Merrimack, Connecticut (forming nearly all of the state’s
western border with Vermont), Piscataqua (separating the southeastern part of the state
from Maine), Saco, Androscoggin, and Ossipee. Politically, the state is divided into 10
counties (Figure 1, Table 1).
2
Figure 1. New Hampshire counties.
3
Table 1. New Hampshire counties and their land area in square miles.
(http://en.wikipedia.org)
Land Area Percent of
County (sq. miles) State Rank
Belknap 401 4.5 9
Carroll 934 10.4 4*
Cheshire 708 7.9 6
Coos 1801 20.1 1
Grafton 1714 19.1 2
Hillsborough 876 9.8 5
Merrimack 934 10.4 3*
Rockingham 695 7.7 7
Strafford 369 4.1 10
Sullivan 537 6.0 8
Total 8,969
*According to the World Almanac and Book of Facts 1992, Merrimack County is slightly
larger than Carroll County (936 sq. miles vs. 933 sq. miles), so the former is ranked
number 3 in area.
4
METHODS
The NWI relies on photointerpretation of aerial photographs to locate and map wetlands
and deepwater habitats. For New Hampshire, most of the aerial photography used was
1:58,000 color infrared captured from the spring of 1985 to the spring of 1987; a few
state border quads have been updated with more recent imagery. With this imagery, the
target mapping unit for wetlands ranges between 1-3 acres. This means that most
wetlands larger than three acres should be mapped and that all wetlands are not mapped.
Even with this target mapping unit established, it must be recognized that aerial
photointerpretation has limitations in terms of the types of wetlands that can be readily
identified (Tiner 1990, 1999) and that larger wetlands of certain types will escape
detection and be missing from the maps. These limitations are generally outlined in
Tables 1 and 2. The effective date of this inventory should be considered the mid-1980s.
Wetlands were classified according to the FWS’s official wetland classification system
(Cowardin et al. 1979). The following categories were identified for wetlands and
deepwater habitats: system, subsystem, class, subclass, water regime, and a few special
modifiers (e.g., partly drained, dike/impounded, excavated, and farmed). The organic
soil modifier “g” was applied to Atlantic white cedar swamps (e.g., PFO4Bg) to highlight
them; the acid modifier “a” was applied to bogs (e.g., PSS3Ba).
Wetland maps were prepared following standard NWI mapping conventions (U.S. Fish
and Wildlife Service 1994, 1995). Data were digitized to create a geospatial database.
NWI data are posted on the web at NWI home page: http://www.fws.gov/nwi/. Data
were summarized by the NWI Mapping Support Center at Madison, Wisconsin. The
following conventions were employed:
1. State and county boundaries were determined using the Geographic Data
Technology’s 1:100K states and counties layers. These were used due to the lack
of a consistent nationwide layer of boundaries at the 1:24,000 scale.
2. All marine deepwater habitats (M1___) were removed from the analysis. The
decision to remove them from the analysis was made due to the lack of validity of
this acreage value. The marine system extends far beyond the mapped area and is
ended at 1:250K quad boundaries rendering the acreage meaningless.
3. Areas where county or state boundaries consisted of two-line waterbodies, (i.e.
rivers, streams) the boundary was identified and digitized directly from a USGS
1:24,000 DRG.
The data was summarized by county and aggregated by state in two categories: 1)
system, subsystem, class, and subclass and 2) system and water regime. Any differences
in state and county totals are due to round-off procedures.
5
Table 1. Major NWI map limitations. (Adapted from Tiner 1999.)
1. Target mapping unit – minimum size wetland that NWI is attempting to map which is
generally related to the scale of the imagery: 1-3 acres for 1:58,000 photography.
2. Spring photography �� aquatic beds and nonpersistent emergent wetlands may be
undermapped since these types are usually obscured by high water. In some cases,
flooded emergents may be misclassified as scrub-shrub wetlands.
3. Forested wetlands – forested wetlands on glacial till are difficult to photointerpret as
are temporarily flooded or seasonally saturated types, especially on the coastal plain and
on glaciolacustrine plains; they may be under-represented by the existing NWI mapping.
Such areas may be identified by examining U.S. Department of Agriculture soil survey
maps for hydric soil map units that are undeveloped (i.e., areas of undeveloped hydric
soil map units that were not mapped by NWI represent areas that may contain wetlands).
4. Estuarine and tidal waters – delineation of the break between estuarine and riverine
(tidal) systems should be considered approximate.
5. Tidal flats – since imagery was not tide synchronized, tidal flat boundaries were based
on aerial photointerpretation in consultation with collateral data such as U.S. Geological
Survey topographic maps.
6. Coastal wetlands – identification of high marsh (irregularly flooded) vs. low marsh
(regularly flooded) in tidal marshes is conservative; photo-signatures are not distinctive
in many instances.
7. Water regimes – water regime classification is based on photo-signatures coupled with
limited field verification; they should be considered approximate.
8. Linear wetlands (long, narrow) – they follow drainageways and stream corridors and
may or may not be mapped depending on project objectives. Most NWI maps identify at
least some of these features, but no attempt was made to map all of them.
9. Partly drained wetlands – they are conservatively mapped; many are not shown on
NWI maps.
10. Aerial photography – imagery reflects wetness during the specific year and season it
was acquired.
11. Drier-end wetlands (temporarily flooded and seasonally saturated types) – they are
difficult to photointerpret; many have been mapped by consulting hydric soil data from
the U.S.D.A. Natural Resources Conservation Service.
12. Mapped boundaries – they may be somewhat different than if based on detailed field
observations, especially in areas with subtle changes in topography.
6
Table 2. Specific problems noted during photointerpretation of New Hampshire
wetlands.
1. High tide and ice-scouring obscured low marsh (E2EM1N) areas along the Merrimack
River. The “Soil Survey of New Hampshire Tidal Marshes” (USDA Soil Conservation
Service 1974) was used to help identify lower limits of salt marshes. This survey plus
field checking were used to help make salt-fresh (Estuarine-Riverine tidal) breaks.
2. Forested wetlands were difficult to identify on some images due to indistinct
signatures or to leaf-out (e.g., May 1986 photos were particularly problematic also for
separating evergreen from deciduous forested wetlands). Soil survey information and
USGS swamp symbols and contours were used to help separate the wet forests from the
upland forests. Mapping of forested wetlands is conservative.
3. E1UB4L was used to classify salt marsh pannes greater than 3 acres in size.
4. Mixed palustrine emergent and scrub-shrub wetlands may underestimate the amount
of shrubby vegetation due to photo-signature.
5. 1986 photos showed a lot more water than appeared on the USGS topographic map
and seemed to have higher water levels than the 1985 photos for neighboring areas.
6. March 1985 photos had some ice on ponds and lakes making classification difficult;
snow on land areas presented similar classification problems. Additional field work in
subject areas was performed to resolve these issues as much as time/budget would permit.
7. Presence of dams on the Connecticut River caused river to be classified as L1UBHh
far upstream due to impoundment effect. Intermittently flooded channels associated with
dams along the Connecticut River were classified as R4 (Riverine Intermittent) habitat.
8. Sewage treatment ponds were classified with “K” (artificial) water regime.
9. Timber harvest (including slash piles) created dark signatures resembling wetland
signature; limited delineations to low areas (depressions).
10. One photo has significant cloud cover requiring interpreters to consult adjacent
photos (overlapping images) to identify wetlands.
11. There may be significant seepage wetlands in mountainous areas as interpreters
noted swamp symbols on USGS topographic maps extending upslope 4-8 contours.
Photointerpreters relied on photo-signatures and soil surveys for inaccessible sites to aid
in mapping which probably led to conservative mapping of these wetland types. USGS
15-minute topographic maps tended to have extensive wetlands via symbology, but
interpreters relied more on photo-signatures as they felt that much of those areas looked
like dry forests at least from a signature standpoint.
7
12. Interpretation of wetlands along the Merrimack River were difficult due to imagery;
USDA soil survey was used to help identify wetlands and classify their water regime.
8
RESULTS
Wetland Maps
NWI maps for New Hampshire were prepared in the 1990s, except for some state border
quads that were done as parts of NWI work in adjacent states. These maps were
produced at a scale of 1:24,000 using the U.S. Geological Survey topographic maps as
base maps. Hardcopy maps are available for purchase through the Office of State
Planning, State of New Hampshire, 2 ½ Beacon Street, Concord, NH 03301 (Attn: Bea
Jillette; 603-271-2155).
After publication of the hardcopy maps, the NWI maps were converted to digital form for
computer access and geographic information system (GIS) applications. Since the 1990s,
the NWI Program has stopped production of hardcopy maps, replacing them with digital
wetland geospatial data. All NWI data are now available online at the NWI website:
http://www.fws.gov/nwi/. Some maps along state lines may have been updated since the
original maps were produced and are available only online. To access NWI data, visit the
NWI website, click on the “Wetlands Mapper”, then click on the map of the lower 48
states, and finally zoom into the location of interest to see the wetland data for a specific
area. Digital NWI data can also be downloaded for GIS use at this website. Digital NWI
data are also available through the state GIS website: http://www.granit.sr.unh.edu/ but
check to make sure that the latest data are posted at this site.
A map showing the distribution of New Hampshire’s wetlands and waters is provided as
Figure 2. This is a reduction of the original map which was produced at a scale of
1:275,000.
9
Figure 2. Map showing the distribution of wetlands and waters of New Hampshire
excluding marine offshore waters. (Note: This is a reduced version of original figure.)
10
State Totals
Wetlands. The NWI identified nearly 290,000 acres of wetlands, covering 5% of the
state’s land area (Table 3). Palustrine wetlands are the main type, totaling about 278,000
acres and representing 96% of the state’s wetland area. Fifty percent of the palustrine
wetlands (or 48% of all wetlands) were forested types, with scrub-shrub wetlands making
up slightly more than one-quarter (26%) of the freshwater wetlands, emergent wetlands
representing 14% of these wetlands, and ponds (unconsolidated bottom and shores)
account for nearly 9%.
Only 8,029 acres of estuarine wetlands occur, occupying nearly 3% of the wetland area.
Emergent wetlands (salt and brackish marshes) were the most common estuarine
wetlands, accounting for 70% of the estuarine wetlands. Unconsolidated shores (tidal
flats) made up 29% of the estuarine wetlands.
Riverine, lacustrine, and marine wetlands when combined account for 2,792 acres which
is roughly 1% of the state’s wetlands. Riverine unconsolidated shores represented most
of this acreage (1,447 acres).
Deepwater Habitats. Approximately 204,000 acres of deepwater habitats were
inventoried, excluding marine waters and waters of linear streams. Lacustrine waters
accounted for 82% of the state’s water area (166,777 acres). Riverine waters were next in
area with 20,260 acres mapped (15 tidal acres, 18,440 lower perennial acres, 1,803 acres
upper perennial acres, and 15 acres of undetermined perennial), followed by 17,087 acres
of estuarine waters.
County Totals
Wetlands. The acreage of wetlands by type is given for each county in Table 4.
Rockingham County had the most wetland acreage with about 61,000 acres inventoried.
Four other counties had over 30,000 acres: Coos, Hillsborough, and Merrimack. The
wetlands in these counties accounted for almost 60% of the state wetlands. The highest
density of wetlands was found in Rockingham County with nearly 14% of its land area
occupied by wetlands (Table 5). Strafford County was next ranked in wetland density
with slightly more than 8% of its land area represented by wetland.
Deepwater Habitats. Belknap County had the highest acreage of deepwater habitat,
followed closely by Carroll County (Table 6). Lake Winnipesaukee, New Hampshire’s
largest lake, was responsible for the predominance of deepwater habitat in these counties.
Belknap County had, by far, the highest proportion of its area occupied by deepwater
habitat – nearly 17%. Strafford and Carroll Counties each had about 6% of their area
covered by deep water. Estuarine waters were nearly equally abundant in Rockingham
and Strafford Counties where they represented a half or more of the deepwater habitats.
11
Table 3. Wetland acreage summaries for the state of New Hampshire. State totals differ
from sum of county totals due to round-off procedures.
Ecological System Wetland Class Acreage
Marine Aquatic Bed 254
------------------------------ ------
Subtotal Vegetated 254
Rocky Shore 18
Unconsolidated Shore 363
------------------------------ ------
Subtotal Nonvegetated 381
Total Marine 635
Estuarine Aquatic Bed 137
Emergent 5,584
------------------------------ ----------
Subtotal Vegetated 5,721
Unconsolidated Shore 2,308
------------------------------ --------
Subtotal Nonvegetated 2,308
Total Estuarine 8,029
Palustrine Aquatic Bed 199
Emergent 38,719
Forested 139,401
Scrub-Shrub 73,506
----------------------------- -------------
Subtotal Vegetated 251,825
Unconsolidated Bottom 26,059
Unconsolidated Shore 55
------------------------------ -------------
Subtotal Nonvegetated 26,114
Total Palustrine 277,939
12
Table 3. Continued
Lacustrine Aquatic Bed 85
Emergent (nonpersistent) 111
-------------------------------- -------------
Subtotal Vegetated 196
Unconsolidated Bottom 170
Unconsolidated Shore 302
--------------------------------- -------------
Subtotal Nonvegetated 472
Total Lacustrine 668
Riverine Unconsolidated Shore 1,447
Rocky Shore 6
Streambed 36
--------------------------------- -----------
Subtotal Nonvegetated 1,489
Total Riverine 1,489
ALL WETLANDS 288,760
13
Table 4. NWI findings for each county. Numbers represent acres of wetlands.
County
NWI Type Belknap Carroll Cheshire Coos Grafton Hillsborough
Palustrine Wetlands
Aquatic Bed 5 11 -- 51 36 28
Emergent 2,319 2,971 3,651 3,275 3,115 7,125
Forested 5,154 16,842 10,610 20,068 8,744 15,864
Scrub-Shrub 3,043 6,369 7,124 14,358 6,225 8,999
Unconsol. Bottom 1,505 1,800 2,564 1,879 2,664 4,598
Lacustrine Wetlands
Aquatic Bed -- -- -- -- -- 42
Emergent -- -- 25 24 29 --
Unconsolidated. Shore 2 -- 5 251 14 13
Unconsolidated Bottom -- -- -- -- 1 86
Riverine Wetlands
Unconsol. Shore 2 350 37 220 681 34
Rocky Shore 2 -- -- -- 1 --
Streambed -- -- 20 3 10 --
Total 12,032 28,343 24,036 40,129 21,520 36,789
14
Table 4 (continued). County
NWI Type Merrimack Rockingham Strafford Sullivan
Palustrine Wetlands
Aquatic Bed 1 30 -- 38
Emergent 5,359 6,677 2,402 1,826
Forested 14,222 32,531 11,040 4,326
Scrub-Shrub 9,706 10,038 4,031 3,615
Unconsol. Bottom 4,267 3,816 1,613 1,407
Lacustrine Wetlands
Aquatic Bed -- 43 -- --
Emergent -- -- 33 --
Unconsolidated. Shore 2 1 -- 15
Unconsolidated Bottom 40 25 -- 18
Riverine Wetlands
Unconsol. Shore 48 -- 1 74
Rocky Shore 2 -- -- --
Streambed 3 -- -- --
Estuarine Wetlands
Aquatic Bed -- 134 3 --
Emergent -- 5,369 215 --
Unconsol. Shore -- 1,864 444 --
Marine Wetlands
Aquatic Bed -- 254 -- --
Unconsol. Shore -- 363 -- --
Rocky Shore -- 18 -- --
Total 33,650 61,163 19,782 11,319
15
Table 5. Ranking of counties by wetland area. Percent of county comprised by wetlands
is also given.
Wetland Percent of County
Rank County Acreage Land Area
1 Rockingham 61,163 13.8
2 Coos 40,129 3.5
3 Hillsborough 36,789 6.6
4 Merrimack 33,650 5.6
5 Carroll 28,343 4.7
6 Cheshire 24,036 5.3
7 Grafton 21,520 2.0
8 Strafford 19,782 8.4
9 Belknap 12,032 4.7
10 Sullivan 11,319 3.3
16
Table 6. Acreage of deepwater habitats in New Hampshire counties. Riverine waters are
separated into lower perennial, upper perennial, and tidal types. Percent of county
occupied by deepwater habitats (both excluding and including marine waters) is given
and rank by acreage.
Lacustrine Riverine Waters Estuarine Total % of
County Waters Lower Upper Tidal Waters Waters of Co. (Rank)
Belknap 42,815 376 13 -- -- 43,204 16.8 (1)
Carroll 37,012 747 151 -- -- 37,910 6.3 (2)
Cheshire 10,290 2,364 125 -- -- 12,779 2.8 (8)
Coos 16,664 3,163 156 -- -- 19,983 1.7 (4)
Grafton 18,402 4,142 595 -- -- 23,139 2.1 (3)
Hillsborough 7,680 2,113 149 -- -- 9,942 1.8 (9)
Merrimack 11,200 2,902 349 -- -- 14,451 2.4 (7)
Rockingham 9,717 139 40 2 8,832 18,730 4.2 (5)
Strafford 6,359 291 128 13 8,255 15,046 6.4 (6)
Sullivan 6,639 2,202 99 -- -- 8,940 2.6 (10)
17
DISCUSSION
Comparison with Hydric Soil Acreage
The U.S.D.A. National Resources Conservation Service has conducted soil surveys for
New Hampshire during which soil scientists have identified wet soils that are now called
“hydric soils.” Over 50 soil series and land types representing potential wetlands have
been mapped since the 1930s (Table 7). While these areas are dominated by hydric soils
(e.g., poorly drained and very poorly drained soils), even soil map units of better drained
soils have some hydric soil as inclusions.
According to the latest soil survey statistics, over 576,000 acres of hydric soils have been
mapped in New Hampshire: 41,112 acres of hydric Entisols (e.g., floodplain soils),
152,119 acres of Histosols (organic soils: peats and mucks), 43,767 acres of Spodosols
(evergreen forest soils), and 339,388 acres of Inceptisols (other mostly forest soils) (Paul
Finnell, USDA NRCS, National Soils Database Manager, pers. comm. 2007). When
compared with the wetlands mapped by NWI, we find a considerable difference in the
acreage in New Hampshire that may be covered by wetlands: 290,000 acres (NWI) vs.
576,000 acres (soil surveys). There are, however, several reasons for the differences
including: 1) more generalized mapping of soils (e.g., larger map units) than the more
detailed mapping of wetlands by NWI, 2) the different dates of the soil surveys vs. NWI
(changes likely have taken place in the presence of wetlands since the original soil
survey), and 3) difficulty in photointerpreting the drier-end wetlands, especially
seasonally saturated forested wetlands (results in conservative mapping by NWI; such
areas are likely shown as hydric soil mapping units on the soil surveys). Overall, the
NWI estimates are conservative due to the limitations in the ability to photointerpret
wetlands (see discussion in Methods), while the soil survey numbers are probably liberal
due to their age and mapping techniques (e.g., minimum mapping sizes and interpretation
of large forest tracts). The conclusion is that the actual extent of wetlands probably lies
somewhere between the two numbers. From the statewide perspective, then, the acreage
of wetlands ranges between 290,000 acres (NWI) and 576,386 acres. Consequently
wetlands may occupy anywhere between 5-10 percent of the state.
18
Table 7. List of hydric soil series and some land types associated with New Hampshire’s
wetlands based on soil survey mapping since the 1930s. (Note: List may not be
complete.)
Alluvial Land, Mixed, Wet Alluvial Land, Wet
Bemis Biddeford
Binghamville Borohemists
Bucksport Burnham
Cabot Charles
Chocorua Cohas
Endoaquents Grange
Greenwood Fresh Water Marsh
Ipswich Kinsman
Leicester (and variant) Lim
Limerick (and variant) Lyme
Maybid Medomak
Monarda Moosilauke
Muck and Peat Naumburg
Ossipee Pawcatuck
Peacham Pemi
Pillsbury Pipestone
Pondicherry Raynham (and variant)
Ridgebury Rippowam
Roundabout Rumney
Saco (and variant) Saugatuck
Scantic Scarboro
Scitico Searsport
Squamscott Stissing
Swanton Tidal Marsh
Vassalboro Walpole
Wareham Westbrook
Whitman Wonsqueak
19
CONCLUSION
The NWI Program mapped about 290,000 acres of wetlands and over 200,000 acres of
deepwater habitats, excluding marine waters, for the state. The wetland mapping is
conservative due to limitations of the photointerpretation techniques employed.
Considering NRCS hydric soil data, the actual extent of wetlands in New Hampshire is
likely somewhere between 290,000 and 576,000 acres, representing 5-10% of the state’s
land area.
20
ACKNOWLEDGMENTS
Numerous individuals contributed to the mapping of New Hampshire’s wetlands.
Wetland photointerpretation was performed by staff at the University of Massachusetts,
Forestry and Wildlife Department: by David Foulis, Robert Popp, George Springston,
David Sumpter, Kim Santos, Michael Kowal, Janice Stone, Glenn Smith, Catherine
Cornell, Tim Moore, Anthony Davis, Gail Shaughnessy, John Organ, Judy Harding, and
Frank Shumway. John Anderson (formerly U.S. Fish & Wildlife Service) also
interpreted a few areas. Ralph Tiner coordinated the inventory for the U.S. Fish and
Wildlife Service (FWS).
Ralph Tiner, John Organ, Bill Zinni, and Glenn Smith (FWS) were responsible for
providing regional quality control of the inventory products during various stages of this
project. Cartographic work was performed under the direction of the FWS’s National
Wetlands Inventory Center, St. Petersburg, Florida. GIS analysis of the data for this
report was done by Mitch Bergeson (U.S. Geological Survey) working for the NWI
Mapping Support Center at Madison, Wisconsin.
Paul R. Finnell, USDA Natural Resources Conservation Service, National Soil Survey
Center, Lincoln, Nebraska provided the summary of hydric soil data for New Hampshire
referenced in this report. Eric Derleth (FWS, New England Field Office) offered his
photograph of the Thompson Sanctuary wetlands (North Sandwich) for use as the cover
for this report.
21
REFERENCES
Bailey, R.G. 1995. Description of the Ecoregions of the United States. U.S.D.A. Forest
Service, Washington, DC. http://www.fs.fed.us/land/ecosysmgmt/ecoreg1_home.html
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service,
Washington, DC. FWS/OBS-79/31.
Tiner, R.W., Jr. 1990. Use of high-altitude aerial photography for inventorying forested
wetlands in the United States. For. Ecol. Manage. 33/34: 593-604.
Tiner, R.W. 1999. Wetland Indicators: A Guide to Wetland Identification, Delineation,
Classification, and Mapping. Lewis Publishers, CRC Press, Boca Raton, FL.
U.S. D.A. Soil Conservation Service. 1974. Soil Survey of New Hampshire Tidal
Marshes. Durham, NH.
U.S. Fish and Wildlife Service. 1995. Photo Interpretation Conventions for the National
Wetlands Inventory. NWI Project, St. Petersburg, FL.
U.S. Fish and Wildlife Service. 1994. Cartographic Conventions for the National
Wetlands Inventory. NWI Project, St. Petersburg, FL.
U.S. Department of the Interior
Fish and Wildlife Service
http://www.fws.gov
September 2007

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Cover Photo: Audubon Society of New Hampshire’s Thompson Sanctuary wetlands by
Eric Derleth, U.S. Fish & Wildlife Service.
New Hampshire Wetlands and Waters:
Results of the National Wetlands Inventory
Ralph W. Tiner
U.S. Fish & Wildlife Service
National Wetlands Inventory Program
Northeast Region
300 Westgate Center Drive
Hadley, MA 01035
August 2007
This report should be cited as:
Tiner, R.W. 2007. New Hampshire Wetlands and Waters: Results of the National
Wetlands Inventory. U.S. Fish and Wildlife Service, Northeast Region, Hadley, MA.
NWI Technical Report. 21 pp.
Note: The findings and conclusions in the report are those of the author and do not
necessarily represent the views of the U.S. Fish and Wildlife Service.
TABLE OF CONTENTS
Page
Introduction 1
Study Area 1
Methods 4
Results 8
Wetland Maps 8
State Totals 9
County Totals 9
Discussion 17
Comparison with Hydric Soils Acreage 17
Conclusion 19
Acknowledgments 20
References 21
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1
INTRODUCTION
The U.S. Fish and Wildlife Service (FWS) has been conducting a nationwide survey of
wetlands and deepwater habitats since the mid-1970s through its National Wetlands
Inventory Program (NWI). This survey is accomplished using traditional
photointerpretation techniques to produces map and digital geospatial data on the status
of wetlands. The U.S. Geological Survey topographic maps serve as the base data upon
which boundaries of wetlands and deepwater habitats are delineated. Wetlands are
classified according to the FWS’s official wetland classification system (Cowardin et al.
1979) which has been adopted as the national standard for reporting on the status and
trends of U.S. wetlands by the Federal Geographic Data Committee
(http://www.fws.gov/stand/standards/wetlands.txt).
Wetland mapping has been completed for over 90% of the coterminous U.S., all of
Hawaii, and 35% of Alaska. For the Northeast, wetland mapping has been completed for
12 of the 13 states in the region; all but New York have been completely mapped. As
time permits, the FWS summarizes the results of its NWI for geographic areas. Detailed
state reports have been prepared for several states (Connecticut, Delaware, Maryland, and
New Jersey), while data summary reports have been prepared for several other states in
the northeastern United States: Massachusetts, Vermont, Pennsylvania, and West
Virginia.
Wetland mapping for New Hampshire was completed in the 1990s and the data have
been available online for several years. The data have not been summarized; this report
provides a summary of the findings of the inventory.
Study Area
The state of New Hampshire encompasses 9,350 square miles in the northeastern United
States. It ranks 46th among states in size and 41th in population as of 2005. The state
contains 8,969 square miles of land and 382 square miles of water
(http://infoplease.com).
From a natural landscape standpoint, the state falls within two of Bailey’s ecoregions:
Adirondack-New England Mixed Forest-Coniferous Forest-Alpine Meadow Province and
Eastern Broadleaf Forest (Oceanic) Province (Bailey 1995). Due to its glacial history,
the state contains numerous lakes and ponds with Lake Winnipesaukee being the largest
(44,586 acres) and the most well-known. It is nearly seven times bigger than New
Hampshire’s next largest lake – Umbagog Lake (7,539 acres). Among the more
prominent rivers are the Merrimack, Connecticut (forming nearly all of the state’s
western border with Vermont), Piscataqua (separating the southeastern part of the state
from Maine), Saco, Androscoggin, and Ossipee. Politically, the state is divided into 10
counties (Figure 1, Table 1).
2
Figure 1. New Hampshire counties.
3
Table 1. New Hampshire counties and their land area in square miles.
(http://en.wikipedia.org)
Land Area Percent of
County (sq. miles) State Rank
Belknap 401 4.5 9
Carroll 934 10.4 4*
Cheshire 708 7.9 6
Coos 1801 20.1 1
Grafton 1714 19.1 2
Hillsborough 876 9.8 5
Merrimack 934 10.4 3*
Rockingham 695 7.7 7
Strafford 369 4.1 10
Sullivan 537 6.0 8
Total 8,969
*According to the World Almanac and Book of Facts 1992, Merrimack County is slightly
larger than Carroll County (936 sq. miles vs. 933 sq. miles), so the former is ranked
number 3 in area.
4
METHODS
The NWI relies on photointerpretation of aerial photographs to locate and map wetlands
and deepwater habitats. For New Hampshire, most of the aerial photography used was
1:58,000 color infrared captured from the spring of 1985 to the spring of 1987; a few
state border quads have been updated with more recent imagery. With this imagery, the
target mapping unit for wetlands ranges between 1-3 acres. This means that most
wetlands larger than three acres should be mapped and that all wetlands are not mapped.
Even with this target mapping unit established, it must be recognized that aerial
photointerpretation has limitations in terms of the types of wetlands that can be readily
identified (Tiner 1990, 1999) and that larger wetlands of certain types will escape
detection and be missing from the maps. These limitations are generally outlined in
Tables 1 and 2. The effective date of this inventory should be considered the mid-1980s.
Wetlands were classified according to the FWS’s official wetland classification system
(Cowardin et al. 1979). The following categories were identified for wetlands and
deepwater habitats: system, subsystem, class, subclass, water regime, and a few special
modifiers (e.g., partly drained, dike/impounded, excavated, and farmed). The organic
soil modifier “g” was applied to Atlantic white cedar swamps (e.g., PFO4Bg) to highlight
them; the acid modifier “a” was applied to bogs (e.g., PSS3Ba).
Wetland maps were prepared following standard NWI mapping conventions (U.S. Fish
and Wildlife Service 1994, 1995). Data were digitized to create a geospatial database.
NWI data are posted on the web at NWI home page: http://www.fws.gov/nwi/. Data
were summarized by the NWI Mapping Support Center at Madison, Wisconsin. The
following conventions were employed:
1. State and county boundaries were determined using the Geographic Data
Technology’s 1:100K states and counties layers. These were used due to the lack
of a consistent nationwide layer of boundaries at the 1:24,000 scale.
2. All marine deepwater habitats (M1___) were removed from the analysis. The
decision to remove them from the analysis was made due to the lack of validity of
this acreage value. The marine system extends far beyond the mapped area and is
ended at 1:250K quad boundaries rendering the acreage meaningless.
3. Areas where county or state boundaries consisted of two-line waterbodies, (i.e.
rivers, streams) the boundary was identified and digitized directly from a USGS
1:24,000 DRG.
The data was summarized by county and aggregated by state in two categories: 1)
system, subsystem, class, and subclass and 2) system and water regime. Any differences
in state and county totals are due to round-off procedures.
5
Table 1. Major NWI map limitations. (Adapted from Tiner 1999.)
1. Target mapping unit – minimum size wetland that NWI is attempting to map which is
generally related to the scale of the imagery: 1-3 acres for 1:58,000 photography.
2. Spring photography �� aquatic beds and nonpersistent emergent wetlands may be
undermapped since these types are usually obscured by high water. In some cases,
flooded emergents may be misclassified as scrub-shrub wetlands.
3. Forested wetlands – forested wetlands on glacial till are difficult to photointerpret as
are temporarily flooded or seasonally saturated types, especially on the coastal plain and
on glaciolacustrine plains; they may be under-represented by the existing NWI mapping.
Such areas may be identified by examining U.S. Department of Agriculture soil survey
maps for hydric soil map units that are undeveloped (i.e., areas of undeveloped hydric
soil map units that were not mapped by NWI represent areas that may contain wetlands).
4. Estuarine and tidal waters – delineation of the break between estuarine and riverine
(tidal) systems should be considered approximate.
5. Tidal flats – since imagery was not tide synchronized, tidal flat boundaries were based
on aerial photointerpretation in consultation with collateral data such as U.S. Geological
Survey topographic maps.
6. Coastal wetlands – identification of high marsh (irregularly flooded) vs. low marsh
(regularly flooded) in tidal marshes is conservative; photo-signatures are not distinctive
in many instances.
7. Water regimes – water regime classification is based on photo-signatures coupled with
limited field verification; they should be considered approximate.
8. Linear wetlands (long, narrow) – they follow drainageways and stream corridors and
may or may not be mapped depending on project objectives. Most NWI maps identify at
least some of these features, but no attempt was made to map all of them.
9. Partly drained wetlands – they are conservatively mapped; many are not shown on
NWI maps.
10. Aerial photography – imagery reflects wetness during the specific year and season it
was acquired.
11. Drier-end wetlands (temporarily flooded and seasonally saturated types) – they are
difficult to photointerpret; many have been mapped by consulting hydric soil data from
the U.S.D.A. Natural Resources Conservation Service.
12. Mapped boundaries – they may be somewhat different than if based on detailed field
observations, especially in areas with subtle changes in topography.
6
Table 2. Specific problems noted during photointerpretation of New Hampshire
wetlands.
1. High tide and ice-scouring obscured low marsh (E2EM1N) areas along the Merrimack
River. The “Soil Survey of New Hampshire Tidal Marshes” (USDA Soil Conservation
Service 1974) was used to help identify lower limits of salt marshes. This survey plus
field checking were used to help make salt-fresh (Estuarine-Riverine tidal) breaks.
2. Forested wetlands were difficult to identify on some images due to indistinct
signatures or to leaf-out (e.g., May 1986 photos were particularly problematic also for
separating evergreen from deciduous forested wetlands). Soil survey information and
USGS swamp symbols and contours were used to help separate the wet forests from the
upland forests. Mapping of forested wetlands is conservative.
3. E1UB4L was used to classify salt marsh pannes greater than 3 acres in size.
4. Mixed palustrine emergent and scrub-shrub wetlands may underestimate the amount
of shrubby vegetation due to photo-signature.
5. 1986 photos showed a lot more water than appeared on the USGS topographic map
and seemed to have higher water levels than the 1985 photos for neighboring areas.
6. March 1985 photos had some ice on ponds and lakes making classification difficult;
snow on land areas presented similar classification problems. Additional field work in
subject areas was performed to resolve these issues as much as time/budget would permit.
7. Presence of dams on the Connecticut River caused river to be classified as L1UBHh
far upstream due to impoundment effect. Intermittently flooded channels associated with
dams along the Connecticut River were classified as R4 (Riverine Intermittent) habitat.
8. Sewage treatment ponds were classified with “K” (artificial) water regime.
9. Timber harvest (including slash piles) created dark signatures resembling wetland
signature; limited delineations to low areas (depressions).
10. One photo has significant cloud cover requiring interpreters to consult adjacent
photos (overlapping images) to identify wetlands.
11. There may be significant seepage wetlands in mountainous areas as interpreters
noted swamp symbols on USGS topographic maps extending upslope 4-8 contours.
Photointerpreters relied on photo-signatures and soil surveys for inaccessible sites to aid
in mapping which probably led to conservative mapping of these wetland types. USGS
15-minute topographic maps tended to have extensive wetlands via symbology, but
interpreters relied more on photo-signatures as they felt that much of those areas looked
like dry forests at least from a signature standpoint.
7
12. Interpretation of wetlands along the Merrimack River were difficult due to imagery;
USDA soil survey was used to help identify wetlands and classify their water regime.
8
RESULTS
Wetland Maps
NWI maps for New Hampshire were prepared in the 1990s, except for some state border
quads that were done as parts of NWI work in adjacent states. These maps were
produced at a scale of 1:24,000 using the U.S. Geological Survey topographic maps as
base maps. Hardcopy maps are available for purchase through the Office of State
Planning, State of New Hampshire, 2 ½ Beacon Street, Concord, NH 03301 (Attn: Bea
Jillette; 603-271-2155).
After publication of the hardcopy maps, the NWI maps were converted to digital form for
computer access and geographic information system (GIS) applications. Since the 1990s,
the NWI Program has stopped production of hardcopy maps, replacing them with digital
wetland geospatial data. All NWI data are now available online at the NWI website:
http://www.fws.gov/nwi/. Some maps along state lines may have been updated since the
original maps were produced and are available only online. To access NWI data, visit the
NWI website, click on the “Wetlands Mapper”, then click on the map of the lower 48
states, and finally zoom into the location of interest to see the wetland data for a specific
area. Digital NWI data can also be downloaded for GIS use at this website. Digital NWI
data are also available through the state GIS website: http://www.granit.sr.unh.edu/ but
check to make sure that the latest data are posted at this site.
A map showing the distribution of New Hampshire’s wetlands and waters is provided as
Figure 2. This is a reduction of the original map which was produced at a scale of
1:275,000.
9
Figure 2. Map showing the distribution of wetlands and waters of New Hampshire
excluding marine offshore waters. (Note: This is a reduced version of original figure.)
10
State Totals
Wetlands. The NWI identified nearly 290,000 acres of wetlands, covering 5% of the
state’s land area (Table 3). Palustrine wetlands are the main type, totaling about 278,000
acres and representing 96% of the state’s wetland area. Fifty percent of the palustrine
wetlands (or 48% of all wetlands) were forested types, with scrub-shrub wetlands making
up slightly more than one-quarter (26%) of the freshwater wetlands, emergent wetlands
representing 14% of these wetlands, and ponds (unconsolidated bottom and shores)
account for nearly 9%.
Only 8,029 acres of estuarine wetlands occur, occupying nearly 3% of the wetland area.
Emergent wetlands (salt and brackish marshes) were the most common estuarine
wetlands, accounting for 70% of the estuarine wetlands. Unconsolidated shores (tidal
flats) made up 29% of the estuarine wetlands.
Riverine, lacustrine, and marine wetlands when combined account for 2,792 acres which
is roughly 1% of the state’s wetlands. Riverine unconsolidated shores represented most
of this acreage (1,447 acres).
Deepwater Habitats. Approximately 204,000 acres of deepwater habitats were
inventoried, excluding marine waters and waters of linear streams. Lacustrine waters
accounted for 82% of the state’s water area (166,777 acres). Riverine waters were next in
area with 20,260 acres mapped (15 tidal acres, 18,440 lower perennial acres, 1,803 acres
upper perennial acres, and 15 acres of undetermined perennial), followed by 17,087 acres
of estuarine waters.
County Totals
Wetlands. The acreage of wetlands by type is given for each county in Table 4.
Rockingham County had the most wetland acreage with about 61,000 acres inventoried.
Four other counties had over 30,000 acres: Coos, Hillsborough, and Merrimack. The
wetlands in these counties accounted for almost 60% of the state wetlands. The highest
density of wetlands was found in Rockingham County with nearly 14% of its land area
occupied by wetlands (Table 5). Strafford County was next ranked in wetland density
with slightly more than 8% of its land area represented by wetland.
Deepwater Habitats. Belknap County had the highest acreage of deepwater habitat,
followed closely by Carroll County (Table 6). Lake Winnipesaukee, New Hampshire’s
largest lake, was responsible for the predominance of deepwater habitat in these counties.
Belknap County had, by far, the highest proportion of its area occupied by deepwater
habitat – nearly 17%. Strafford and Carroll Counties each had about 6% of their area
covered by deep water. Estuarine waters were nearly equally abundant in Rockingham
and Strafford Counties where they represented a half or more of the deepwater habitats.
11
Table 3. Wetland acreage summaries for the state of New Hampshire. State totals differ
from sum of county totals due to round-off procedures.
Ecological System Wetland Class Acreage
Marine Aquatic Bed 254
------------------------------ ------
Subtotal Vegetated 254
Rocky Shore 18
Unconsolidated Shore 363
------------------------------ ------
Subtotal Nonvegetated 381
Total Marine 635
Estuarine Aquatic Bed 137
Emergent 5,584
------------------------------ ----------
Subtotal Vegetated 5,721
Unconsolidated Shore 2,308
------------------------------ --------
Subtotal Nonvegetated 2,308
Total Estuarine 8,029
Palustrine Aquatic Bed 199
Emergent 38,719
Forested 139,401
Scrub-Shrub 73,506
----------------------------- -------------
Subtotal Vegetated 251,825
Unconsolidated Bottom 26,059
Unconsolidated Shore 55
------------------------------ -------------
Subtotal Nonvegetated 26,114
Total Palustrine 277,939
12
Table 3. Continued
Lacustrine Aquatic Bed 85
Emergent (nonpersistent) 111
-------------------------------- -------------
Subtotal Vegetated 196
Unconsolidated Bottom 170
Unconsolidated Shore 302
--------------------------------- -------------
Subtotal Nonvegetated 472
Total Lacustrine 668
Riverine Unconsolidated Shore 1,447
Rocky Shore 6
Streambed 36
--------------------------------- -----------
Subtotal Nonvegetated 1,489
Total Riverine 1,489
ALL WETLANDS 288,760
13
Table 4. NWI findings for each county. Numbers represent acres of wetlands.
County
NWI Type Belknap Carroll Cheshire Coos Grafton Hillsborough
Palustrine Wetlands
Aquatic Bed 5 11 -- 51 36 28
Emergent 2,319 2,971 3,651 3,275 3,115 7,125
Forested 5,154 16,842 10,610 20,068 8,744 15,864
Scrub-Shrub 3,043 6,369 7,124 14,358 6,225 8,999
Unconsol. Bottom 1,505 1,800 2,564 1,879 2,664 4,598
Lacustrine Wetlands
Aquatic Bed -- -- -- -- -- 42
Emergent -- -- 25 24 29 --
Unconsolidated. Shore 2 -- 5 251 14 13
Unconsolidated Bottom -- -- -- -- 1 86
Riverine Wetlands
Unconsol. Shore 2 350 37 220 681 34
Rocky Shore 2 -- -- -- 1 --
Streambed -- -- 20 3 10 --
Total 12,032 28,343 24,036 40,129 21,520 36,789
14
Table 4 (continued). County
NWI Type Merrimack Rockingham Strafford Sullivan
Palustrine Wetlands
Aquatic Bed 1 30 -- 38
Emergent 5,359 6,677 2,402 1,826
Forested 14,222 32,531 11,040 4,326
Scrub-Shrub 9,706 10,038 4,031 3,615
Unconsol. Bottom 4,267 3,816 1,613 1,407
Lacustrine Wetlands
Aquatic Bed -- 43 -- --
Emergent -- -- 33 --
Unconsolidated. Shore 2 1 -- 15
Unconsolidated Bottom 40 25 -- 18
Riverine Wetlands
Unconsol. Shore 48 -- 1 74
Rocky Shore 2 -- -- --
Streambed 3 -- -- --
Estuarine Wetlands
Aquatic Bed -- 134 3 --
Emergent -- 5,369 215 --
Unconsol. Shore -- 1,864 444 --
Marine Wetlands
Aquatic Bed -- 254 -- --
Unconsol. Shore -- 363 -- --
Rocky Shore -- 18 -- --
Total 33,650 61,163 19,782 11,319
15
Table 5. Ranking of counties by wetland area. Percent of county comprised by wetlands
is also given.
Wetland Percent of County
Rank County Acreage Land Area
1 Rockingham 61,163 13.8
2 Coos 40,129 3.5
3 Hillsborough 36,789 6.6
4 Merrimack 33,650 5.6
5 Carroll 28,343 4.7
6 Cheshire 24,036 5.3
7 Grafton 21,520 2.0
8 Strafford 19,782 8.4
9 Belknap 12,032 4.7
10 Sullivan 11,319 3.3
16
Table 6. Acreage of deepwater habitats in New Hampshire counties. Riverine waters are
separated into lower perennial, upper perennial, and tidal types. Percent of county
occupied by deepwater habitats (both excluding and including marine waters) is given
and rank by acreage.
Lacustrine Riverine Waters Estuarine Total % of
County Waters Lower Upper Tidal Waters Waters of Co. (Rank)
Belknap 42,815 376 13 -- -- 43,204 16.8 (1)
Carroll 37,012 747 151 -- -- 37,910 6.3 (2)
Cheshire 10,290 2,364 125 -- -- 12,779 2.8 (8)
Coos 16,664 3,163 156 -- -- 19,983 1.7 (4)
Grafton 18,402 4,142 595 -- -- 23,139 2.1 (3)
Hillsborough 7,680 2,113 149 -- -- 9,942 1.8 (9)
Merrimack 11,200 2,902 349 -- -- 14,451 2.4 (7)
Rockingham 9,717 139 40 2 8,832 18,730 4.2 (5)
Strafford 6,359 291 128 13 8,255 15,046 6.4 (6)
Sullivan 6,639 2,202 99 -- -- 8,940 2.6 (10)
17
DISCUSSION
Comparison with Hydric Soil Acreage
The U.S.D.A. National Resources Conservation Service has conducted soil surveys for
New Hampshire during which soil scientists have identified wet soils that are now called
“hydric soils.” Over 50 soil series and land types representing potential wetlands have
been mapped since the 1930s (Table 7). While these areas are dominated by hydric soils
(e.g., poorly drained and very poorly drained soils), even soil map units of better drained
soils have some hydric soil as inclusions.
According to the latest soil survey statistics, over 576,000 acres of hydric soils have been
mapped in New Hampshire: 41,112 acres of hydric Entisols (e.g., floodplain soils),
152,119 acres of Histosols (organic soils: peats and mucks), 43,767 acres of Spodosols
(evergreen forest soils), and 339,388 acres of Inceptisols (other mostly forest soils) (Paul
Finnell, USDA NRCS, National Soils Database Manager, pers. comm. 2007). When
compared with the wetlands mapped by NWI, we find a considerable difference in the
acreage in New Hampshire that may be covered by wetlands: 290,000 acres (NWI) vs.
576,000 acres (soil surveys). There are, however, several reasons for the differences
including: 1) more generalized mapping of soils (e.g., larger map units) than the more
detailed mapping of wetlands by NWI, 2) the different dates of the soil surveys vs. NWI
(changes likely have taken place in the presence of wetlands since the original soil
survey), and 3) difficulty in photointerpreting the drier-end wetlands, especially
seasonally saturated forested wetlands (results in conservative mapping by NWI; such
areas are likely shown as hydric soil mapping units on the soil surveys). Overall, the
NWI estimates are conservative due to the limitations in the ability to photointerpret
wetlands (see discussion in Methods), while the soil survey numbers are probably liberal
due to their age and mapping techniques (e.g., minimum mapping sizes and interpretation
of large forest tracts). The conclusion is that the actual extent of wetlands probably lies
somewhere between the two numbers. From the statewide perspective, then, the acreage
of wetlands ranges between 290,000 acres (NWI) and 576,386 acres. Consequently
wetlands may occupy anywhere between 5-10 percent of the state.
18
Table 7. List of hydric soil series and some land types associated with New Hampshire’s
wetlands based on soil survey mapping since the 1930s. (Note: List may not be
complete.)
Alluvial Land, Mixed, Wet Alluvial Land, Wet
Bemis Biddeford
Binghamville Borohemists
Bucksport Burnham
Cabot Charles
Chocorua Cohas
Endoaquents Grange
Greenwood Fresh Water Marsh
Ipswich Kinsman
Leicester (and variant) Lim
Limerick (and variant) Lyme
Maybid Medomak
Monarda Moosilauke
Muck and Peat Naumburg
Ossipee Pawcatuck
Peacham Pemi
Pillsbury Pipestone
Pondicherry Raynham (and variant)
Ridgebury Rippowam
Roundabout Rumney
Saco (and variant) Saugatuck
Scantic Scarboro
Scitico Searsport
Squamscott Stissing
Swanton Tidal Marsh
Vassalboro Walpole
Wareham Westbrook
Whitman Wonsqueak
19
CONCLUSION
The NWI Program mapped about 290,000 acres of wetlands and over 200,000 acres of
deepwater habitats, excluding marine waters, for the state. The wetland mapping is
conservative due to limitations of the photointerpretation techniques employed.
Considering NRCS hydric soil data, the actual extent of wetlands in New Hampshire is
likely somewhere between 290,000 and 576,000 acres, representing 5-10% of the state’s
land area.
20
ACKNOWLEDGMENTS
Numerous individuals contributed to the mapping of New Hampshire’s wetlands.
Wetland photointerpretation was performed by staff at the University of Massachusetts,
Forestry and Wildlife Department: by David Foulis, Robert Popp, George Springston,
David Sumpter, Kim Santos, Michael Kowal, Janice Stone, Glenn Smith, Catherine
Cornell, Tim Moore, Anthony Davis, Gail Shaughnessy, John Organ, Judy Harding, and
Frank Shumway. John Anderson (formerly U.S. Fish & Wildlife Service) also
interpreted a few areas. Ralph Tiner coordinated the inventory for the U.S. Fish and
Wildlife Service (FWS).
Ralph Tiner, John Organ, Bill Zinni, and Glenn Smith (FWS) were responsible for
providing regional quality control of the inventory products during various stages of this
project. Cartographic work was performed under the direction of the FWS’s National
Wetlands Inventory Center, St. Petersburg, Florida. GIS analysis of the data for this
report was done by Mitch Bergeson (U.S. Geological Survey) working for the NWI
Mapping Support Center at Madison, Wisconsin.
Paul R. Finnell, USDA Natural Resources Conservation Service, National Soil Survey
Center, Lincoln, Nebraska provided the summary of hydric soil data for New Hampshire
referenced in this report. Eric Derleth (FWS, New England Field Office) offered his
photograph of the Thompson Sanctuary wetlands (North Sandwich) for use as the cover
for this report.
21
REFERENCES
Bailey, R.G. 1995. Description of the Ecoregions of the United States. U.S.D.A. Forest
Service, Washington, DC. http://www.fs.fed.us/land/ecosysmgmt/ecoreg1_home.html
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service,
Washington, DC. FWS/OBS-79/31.
Tiner, R.W., Jr. 1990. Use of high-altitude aerial photography for inventorying forested
wetlands in the United States. For. Ecol. Manage. 33/34: 593-604.
Tiner, R.W. 1999. Wetland Indicators: A Guide to Wetland Identification, Delineation,
Classification, and Mapping. Lewis Publishers, CRC Press, Boca Raton, FL.
U.S. D.A. Soil Conservation Service. 1974. Soil Survey of New Hampshire Tidal
Marshes. Durham, NH.
U.S. Fish and Wildlife Service. 1995. Photo Interpretation Conventions for the National
Wetlands Inventory. NWI Project, St. Petersburg, FL.
U.S. Fish and Wildlife Service. 1994. Cartographic Conventions for the National
Wetlands Inventory. NWI Project, St. Petersburg, FL.
U.S. Department of the Interior
Fish and Wildlife Service
http://www.fws.gov
September 2007